http://fivethirtyeight.com/features/bmi-is-a-terrible-measure-of-health/
BMI Is A Terrible Measure Of HealthBut we keep using it anyway.By KATHERINE HOBSON
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Although the merits of w:h over BMI will be familiar to most of you, this article is worth reading as some of the specific stats are surprising.
The researchers analyzed the health data for 15,184 adults who were part of the National Health and Nutrition Examination Survey. Their results,published in the Annals of Internal Medicine, were pretty surprising: They showed that midsection obesity was a killer, even among people with normal BMIs.For example, a man with a BMI of 22 (putting him firmly in the normal range) but too much belly fat according to his waist-to-hip ratio had an 87 percent higher mortality risk than a guy with the same BMI and a healthy waist-to-hip ratio.What’s more, a man with a normal BMI and disproportionately big belly had more than twice the mortality risk of a man who was overweight or obese by BMI but not by waistline. Among women, those who were normal weight by BMI but had a high waist-to-hip ratio had a 48 percent higher mortality risk than those with a similar BMI but a healthy waist-to-hip ratio, and a 32 percent higher risk compared with those who were obese according to BMI only.
Seems likely to me that you can estimate risk best using all four easily measured factors (height, weight, hip, waist) but that it is unlikely to be represented by a simple function: you’d probably need to use a set of spline-functions. However, these days, there is not much need for mathematical simplicity. Everyone is carrying a powerful computer in their pocket, and a simple app could calculate “cardiovascular risk factor”, based on known mortality data, from age, sex, height, weight, hip, waist.
